Anode assembly



Nov. 2, 1965 J. J. I AlNsoN 3,215,613

ANODE ASSEMBLY F'iled Sept. 15, 1960 3 Sheets-Sheet, 1

J. J. LAINSON Nov. 2, 1965 ANODE ASSEMBLY 5 Sheets-Sheet 2 Filed Sept.15. 1960 F/ci daf/N J. AM/50N rrafeA/E/ Nov. 2, 1965 Filed Sept. 15.1960 J. J. LAINSON ANODE ASSEMBLY 3 Sheets-Sheet 5 United States PatentO 3,215,613 ANODE ASSEMBLY John J. Lainson, Hastings, Nebr., assigner toWestern Plastics Corporation, Hastings, Nebr., a corporation of YNebraska Filed Sept. 15, 1960, Ser. No. 56,263 3 Ciams. (Cl. 204-196)This invention relates to improved methods and apparatus forestablishing and maintaining electrical circuit connections in corrosiveand other harmful environments. The various structural features andmethod steps of this invention lare particularly adapted for use incathodic protection systems for reducing corrosive deterioration inunderground and underwater metallic structures.

Corrosion of natural gas pipelines, for example, results in substantialindustrial losses each year. Accordingly, natural gas transmissionsystems are engineered before installation with a view toward improvingoperational reliability by minimizing the rate of corrosion due tomoisture, soil chemicals and electrolytic current.

Corrosion of metals in soil or water is principally an electro-chemicalprocess. The corrosion or metal loss is directly related to the directcurrent discharged from the metal surface at a metal/electrolytejunction. Potential differences exist or develop on the metal/electrolyte junction surface of most structural metals when they areimmersed in an electrolyte such as soil or water. These potentialdiiferences produce a battery action and current flow results.

Corrosion takes place where the metallic ions are discharged from themetallic surface at the metal/ electrolyte junction. This junction ofionic discharge is called an anodic area. In conjunction with thisaction, ions from the electrolyte are accepted or transformed atadjacent or remote metallic surfaces that are less electronegative. Thelatter junction is called a cathodic area.

The anodic areas of the steel pipe used in an underground natural gastransmission system are subject to severe corrosion which must beminimized if the system is to be operated reliably and economically.Accordingly, a considerable body of art has developed in which anodeelectrodes are buried adjacent the pipeline to be protected. The outputvoltage of a direct-current power supply is applied to the anodes andthe pipeline with such a polarity that anodic areas are substantiallyeliminated from the pipeline surfaces. This arrangement reverses theelectrolytic action which would otherwise take place. The anodes,therefore, are expended in preference to expending the steel pipeline.The foregoing approach to corrosion abatement is called cathodicprotection.

vExperience in the pipeline transmission industry has shown that anodesburied in deep ground beds are to be preferred to anodes placed near theearths surface. In general, the use of deep anodes permits buildinglowresistance ground beds in favorable conducting strata underlying highresistivity surface soils that are unsuitable for cathodic protection.

Deep anode ground beds are usually more expensive to install thanshallow beds. Additionally, once the anodes are installed they arerelatively inaccessible. Repair work on the anodes and their associatedconductors, which are usually interconnected in strings, is at bestdiicult and at worse, with some ground bed designs, impossible so thatabandonment of the installation is necessary.

Although many ground bed and anode string arrangements appear in theprior art, substantially all require electrical conductors to connectthe anodes in a multiple circuit connection relative one another.Unfortunately, conductor wire splices must be made to join theindividual anode leads to a main trunk or riser conductor. Addition-3,2l5,6l3 Patented Nov. 2, 1965 ally, the individual anode leads, whichare usually copper wire, must be connected to the dissimilar metal ofthe anode. The conductor splices and the anode lead connections aresubject to severe corrosion due to electrolytic action. Accordingly,these points of electrical connection must be effectively isolated fromthe electrolytic action resulting from their being embedded in moistsoil and possibly under water.

The loss in transmission line investment due to a single splice failurecan be tremendous particularly in the case of a deep anode bed. In manyinstallations the anode string is buried at a depth of several hundredfeet. A splice failure in these installations cannot be repaired, andtherefore the an-ode bed must be abandoned with a resulting loss ofseveral thousands of dollars. Additionally, in the event the cathodicprotection system has been disabled for a considerable period of time,corrosion will substantialy reduce the life of the pipeline.

Heretofore, substantially all conductor splices and anode connections incathodic protection systems have been protected by insulating tapesfabricated from various materials and adhesives. Many splices and anodeconnections thus protected ultimately corrode due to moisture leakagethrough the many overlap seams of the tap layers, and also due toimperfect seals between the conductor sheath and the tape.

Accordingly, a principal object of this invention is to improve thereliability of electrical connections subject to corrosive environments,such as are found in cathodic protection systems for undergroundmetallic structures.

Another object is to provide an improved protective sealing sleeve foran electrical conductor splice which is to be buried underground andsubjected to relatively high water pressures. Another object is toprovide an improved protective sleeve design having basic elements whichmay be used in a group of similar protective sleeves, each adapted toreceive different numbers of spliced conductors.

Another object is to provide a protective cap for sealing the anode leadconnection to the anode of a cathodic protection system. l

Another object is to provide a protective sealing sleeve and aprotective cap as outlined in the prior objects, both of which have manyinterchangeable elements.

Another object is to provide an improved method and apparatus forsubjecting electrical connections to inert gases which will minimizecorrosion tending to destroy the connections.

A first feature of this invention is directed to a protective sleeve forhermetically sealing an electrical cable splice which m-ay be buriedseveral hundred feet. This protective sleeve is particularly adapted foruse in enclosing the necessary splices which must be made lbetween theriser conductors and the anode leads of cathodic protectioninstallations used in natural gas transmission pipelines. In a preferredembodiment, the protective sleeve comprises an insulating tube ofplastic which encloses the cable `splice to be hermetically sealed. Apair of bushings plug each yend of the bore of the tube, and a sealingring is sandwiched between the individual bushings of each pair so thatthe sealing ring is maintained in compression between the bushings andthe exterior insulation cover Iof a spliced con-ductor. In view of thefact that the foregoing structure may be readily assembled in eldinstallation Iby a simple manual operation, the protective sleeve isreadily adapted for the many and varied circuit arrangements which arisein anode installations.

A `second feature of this invention relates to a protective cap forhermetically sealing the anode lead at its point of connection to lananode employed in a cathodic protection system. A preferred embodimentcomprises a cap which is seated upon the terminal end of the anode towhich the anode lead is connected Inasmuch as the connection joint tothe anode lead involves dissimilar metals, for example, -copper tomagnesium, this connection is readily subject to breaking due tocorrosion. The anode lead is therefore sealed to the cap by use of thesame lbushing arrangement previously employed in the protective sleevefor cable splices. Additionally, an anode bushing forcibly compresses asealing ring against the anode surf-ace so as to contain the anode leadconnection within a hermetically sealed cavity. In view of the fact thatthe protective sleeve and the protective anode cap of this inventioncontain identical bushing parts, field installation is greatlyfacilitated without the necessity of maintaining a large number ofdifferent parts.

While the foregoing protective sleeve and cap are admirably suited toaccomplish their intended functions in the usual installation, a thirdfeature of this invention further insures the reliability of a cathodicprotective system. This feature employs interstices between theindividual strands of the cables employed in the riser conductors andanode leads to transmit an inert gas to all splices and anode leadconnections. The use of stranded cables, hermeti-cally sealed protectivesleeves to enclose all splices, and hermetically `sealed anode caps toenclose all anode lead connections provides a gas passage for subjectingall of the electrical conductors and connections to an atmosphere ofinert gas. The presence of this gas tends to substantially eliminate allmoisture and other corrosive elements from making contact with circuitwires, splices, Iand connection joints. It is to be noted, however, thatthe protective sleeve and the protective cap of this invention may beadvantageously employed without recourse to the inert gas feature. It isonly injthose installations in which extreme Water conditions prevailand in which a long life is absolutely necessary, that the use of aninert gas as above described is recommended.

In order that all of the structural features for attaining the objectsof this invention may be understood, reference is herein made to thefollowing drawings wherein:

FIGURE 1 is a simplified diagram of a deep anode installationincorporating the protective sleeve, protective cap, and inert gasfeatures of this invention in a cathodic protection system for a naturalgas transmission pipeline;

FIGURE 2 is a sectional view of the protective sleeve of this inventionadapted for hermetically sealing a straight splice;

FIGURE 3 is a sectional view of a modification of the protective Vsleeveshown in FIGURE 2, which is adapted for hermetically sealing a multipleconductor splice;

FIGURE 4 is an end view of the lstructure shown in FIGURE 3;

FIGURE 5 is an enlarged sectional view showing the manner in which thebushings employed in the protective sleeves of FIGURES 2 and 3, and theprotective cap of FIGURE 7, compress a sealing ring to establish aconductor seal;

FIGURE 6 is an enlarged sectional View showing the annular sealing ringgroove of a lsealing ring bushing;

FIGURE 7 is a sectional View of a protective cap associated with ananode rod to hermetically seal the anode lead connection joint;

FIGURE 8 is a side view of a cable employing a plurality of wirestrands;

FIGURE 9 is an end view showing the interstices between wire strands;and

yFIGURE 10 is a View of an inert gas coupling for connecting a source ofpressurized gas to electrical riser conductors employing strandedcables.

Referring now to the cathodic protection system shown in FIGURE l, deepanode installation 10 is located in the right-of-way for gastransmission pipeline 11. Inasmuch as pipeline 11 is fabricated of steeland is also located underground, it is subject to electrolyticcorrosion. The ground bed for installation 1t) is prepared by drilling ahole 12 by conventional means, such as a rotary rig. Hole 12 is heldopen with drilling mud until the two anode strings 13 and 14 are loweredinto hole 12.

Anode string 13 comprises individual anodes 13a 13b, 13C' 13d and 13e.Anode string 14 comprises individual anodes 14a, 14b, 14C, 14d and 14e.The -anodes are usually fabricated of such materials as magnesium,graphite or silicon. The anodes of each string are electricallyconnected in multiple. Main trunk or riser conductor 15, together withanode leads 16, connect anodes 13a through 13e in multiple; and maintrunk or riser conductor 1'7, together with anode leads 18, connectanodes 14a through 14e in multiple. Both riser conductor 15, togetherwith anode leads 16, connect anodes single pieces without splices. Theconductors have an outer insulation cover which must have adequatemechanical properties to withstand the rigors of direct burial for theexpected life of the installation. Stranded cable having a plurality ofwire strands Z0 (FIGURES 8 andV 9) is also better able to meet theforegoing requirements than cables employing a single solid wire.Inasmuch as the strands 20 are subject to electrolytic corrosion, thecover must provide inherent moisture resistance of a high order so as tohermetically seal the wire strands 20 from the external enviroment. Apreferred cover comprises an inner insulation layer 21 of polyethylene,and an outer sheath 19 of polyvinyl chloride.

A cable having a metallic sheath over the insulation, such as lead,protected by layers of jute, galvanized steel tapes, jute and asphaltictype material offers the maximum assurance that circuit difficultieswill not develop through either mechanical damage, moisture, or chemicaldiffusion. It is, however, a costly construction and cannot be justiedin cathodic protection systems for that reason.

Rubber-neoprene insulations or to a greater extent polyvinyl chlorideresin have found use chiey because of the lower cost. Constructions ofthis sort have given reasonable service, however certain limitations totheir use have lead to the developement of a cable having definiteadvantages for most applications.

A combination of polyethylene and polyvinyl chloride resin is nowemployed for this service. Polyethylene stands unchallenged as the bestinsulation in wet locations. The polyvinyl chloride sheath or protectivejacket over the polyethylene affords a barrier to injury of theinsulation due to mechanical damage and other factors encountered.

The anode leads 16 and 18 are also preferably of the same cableconstruction as riser conductors 15 and 17. The anode leads 16 and 18must necessarily be spliced to riser conductors 15 and 17. Additionally,the anode leads must be connected to their associated anodes. Thesplicers and the anode connections are particularly subject to harmfulenvironmental conditions inasmuch as there must be a break in theinsulation cover in the connection areas. Accordingly, the cable splicesare located within :and sealed by protective sleeves 25 and 26. Like-Wise, the anode connections are located within and sealed by protectivecaps 27. The construction details for protective sleeves 25 and 26(FIGURES 2 and 3), and protective caps 27 (FIGURE 7) are set fourthhereinafter.

In view of the fact that hole 12 for installation 10 is of the order ofthree hundred to tive hundred feet deep, the necessary electricalconnections, including preparation of splices and installation of theprotective sleeves and caps must be made at ground level as a fieldinstallation. The anodes 13 and 14 are rigidly clamped to pipe section28 by clamps 29. The clamped anodes thus are incapable of exertingexcessive pulling on the riser conductors 15 and 17 and the anode leads16 as the anode strings 13 and 14 are lowered into hole 12. One or moreadditional pipe sections 30 are coupled to pipe section 28 by means ofcoupling such as 31, so that the interconnected anode strings may becarefully lowered into hole 12. Centering vane 32 appropriately guidespipe section 28 so that the anodes and the associated electrical systemdo not scrape the inside wall of hole 12. Hole 12 is ultimately backlled with mud. Various other steps, not essential to an understanding ofthe present invention may also be taken, in the preparation of the anodebed, in order to insure proper conduction between the anodes and theearth strata in which they are buried.

Riser conductors 15 and 17 are spliced together within inert gascoupling 35 (FIGURE l0). Cable 36 having a single solid wire core 37 isalso connected to the joint formed by splicing riser conductors 15 and17. The terminal end of conductor 36 removed from inert gas coupling 35is connected to the positive output terminal of a direct-current powersupply 38. The negative output terminal of power supply 38 is connecteddirectly to gas pipeline 11 through stranded cable conductor 40. Theinput terminals of power supply 38 are connected to alternating-currentline conductors 41 and 42. Corrosion of pipeline 11 is substantiallyeliminated by the foregoing cathodic protection circuit. The exposedsurfaces of pipeline 11 are converted into cathodic areas. The surfaceof anodes 13 and 14 define anodic areas which are subject todeterioration resulting from electrolytic action. The sacrice of anodemetal, however, preserves the steel pipeline 11.

Protective sleeves 25 and 26, and protective caps 27 in many anode bedsare buried several hundred feet deep and are subject to water pressuresof several hundred pounds per square inch. This environment may lead tobreakdown in the hermetic seals of sleeves 25 and 26, and caps 27.Additionally, the hermetic seal of the insulation coverings of cableconductors 15, 16, 17 and 18 may also be destroyed causing an opencircuit due to corrosion of the conductor wires. It has been discoveredthat the life and the reliability of anode bed installations may begreatly improved by subjecting all underground wires, splices, and anodelead joints to an inert gas having a pressure at least equal to theenvironmental pressures to which the exposed ksurfaces of the insulationcoverings, protective sleeves and protective caps are subjected. Theinterstices 45 (FIGURE 9) between wire strands 20 are capable ofdelivering an inert gas having the required pressure a distance ofseveral thousand feet. Accordingly, cables 15, 16, 17 and 18 serve adual function of establishing the necessary circuit connections and toconvey inert gas for safeguarding these circuit connections.

Although nitrogen is the most commonly used gas for protectingelectrical circuits, a required supply of nitrogen cannot always bemaintained .at a remote anode installation for natural gas pipelines.The novel c'athodic protection system of FIGURE l employs natural gas asthe required gaseous medium. The inlet of compressor 46 is connected topipeline 11 by metallic pipe 47. The outlet of compressor 46 isconnected to inert gas coupling 35 by metallic pipes 48 and 49 throughpressure regulator 50.

Inert gas coupling 35 comprises a cylindrical tube section 51 havinginternally threaded ends to which end caps 52 and 53 are coupled bymeans of their mating threads. End cap 52 is formed with two accessopenings (not shown) which are plugged by'mated bushing pairs 55 and 56.Bushing pairs 55 and 56 seal riser conductors 15 and 17, respectively.End cap 53 is also formed with two access openings. Bushing pair 57plugs one of these access openings and pipe 49 is coupled to the other.Bushing pair 57 seals positive conductor 36. The detailed structure ofbushing pairs 55, 56 and 57 is shown in FIGURES :and 6 to be describedhereinafter.

Inert gas coupling 35 denes a hermetically sealed cavity 60 having a gasinlet at the opening of pipe 49.

Gas is released from the coupling only through the interstices 45(FIGURE 9) appearing between the wire strands of riser conductors 15 and17. In view of the fact that conductor 36 has only a single conductorhermetically sealed to its outer covering, gas is not transmittedthrough bushing pair 57.

Tube section 51 and end caps 52 and 53 are preferably fabricated of aplastic having a high burst pressure, such as Teon. In the eventcoupling 35 is to be subjected to the relatively high gas pressuresrequired for deep anode installations, parts 51, 52 and 53 should beconstructed of a metal, such as stainless steel.

Bushing pairs 55, 56 and 57 are preferably fabricated from a plastic,such as Kralastic, although these parts can be fabricated from stainlesssteel if pressure requirements so dictate. Each fbushing pair comprisesan end plug bushing 60 (FIGURE 5) and a sealing ring bushing 61. Thellower shank portion of end plug bushing 60 is formed with a standardpipe thread 62 which is coupled to an internal mating thread lining thebores of the laccess openings (not shown) formed in end caps 52 and 53.The upper portion of end plug bushing 60 is formed with an internallythreaded counterbore which receives the lower threaded shank portion 63of seal-ing ring bushing 61. An annular sealing ring groove 64 (FIGURE6) is defined lby projecting lip 65. This groove houses sealing ring 66,which may be a neoprene Oring. Bushings 61 and 60 are formed withaligned conductor feedthrough lholes through which the sealed conductorspass.

Sealing ring bushing 61 has a wrench head 67 of square cross-section(FIGURE 4). The application of a wrench turning force to this headcompresses sealing ring 66 between its adjacent bushing surfaces causingthe sealing ring to project into the conductor passageway formed by thebushing feed-through holes, thereby to lit closely around and toestablish a hermetic seal with the insulation covering of the bushingcontained conductor.

The protect-ive sleeve 26 shown in FIGURE 2 is adapted to hermeticallyseal the straight splice joining riser conductor 15 to anode lead 16 foranode 13e, and also the straight splice joining riser conductor 17 toanode lead 18 for anode 14e. Protective sleeve 26 comprises acylindrical tube 70 having internally threaded ends. A threaded end cap71 closes the upper opening of the bore for tube 70, andra threaded endcap 72 closes the lower opening of the bore for tube 70. Each of the endcaps is formed with a threaded access opening for receiving a bushingpair 60-61 as shown in FIGURE 5. A sealing ring, corresponding sealingring 66 of FIGURE 5, forms a seal with each associated conductor,thereby hermetically sealing the contained splice. The flanges of endcaps 71 and 72 are formed with holes 75 for receiving the round pins ofa spanner wrench used to tighten the caps The protective sleeve 25 shownin FIGURES 3 and 4 is a modication of the sleeve shown in FIGURE 2 whichis adapted to hermetically seal a multiconductor splice, such as theT-joint splice connecting riser conductor 15 to anode leads 16 foranodes 13a through 13d and the T-joint splice connecting riser conductor17 to anode leads 18 for anodes 14a through 14d.

Protective sleeve 25 comprises a cylindrical tube 80 having internallythreaded ends. A threaded end cap 81 closes the upper opening of thebore of tube 80, and a threaded end cap 82 closes the lower opening ofthe bore of tube 80. Each of the end caps is formed with two threadedaccess openings for receiving a bushing pair 60-61 as shown in FIGURE 5,with the exception of the right access opening of end cap 81. In view ofthe fact that protective sleeve 25 is to house a T-joint splice, one ofthe upper access openings is appropriately sealed by a threaded plug 85.A sealing ring, corresponding with sealing ring 66 of FIGURE 5, forms aseal with each conductor associated with a bushing pair 60-61.

The tubes and end caps of protective sleeves 70 and 86 may be fabricatedof a plastic, such as Teflon. Although metal parts may be employed, ifthe conductive characteristics of metal can be tolerated.

In the preparation of a plurality of sequentially disposed T-jointsplices, the main trunk conductor, such as riser conductors and 17should preferably not be cut. Protective sleeve 25 meets thisrequirement, and at the same time can be installed in a simple fieldoperation as follows.

The outer insulation covering of riser conductor 15 or 17 is removed intwo or three inch sections 88 (FIGURE 3) at every cable point 'a spliceis to be made. The necessary bushing pairs 60-61 (loosely coupledrelative one another so as not to force sealing ring 66 against theinsulation covering and removed from their associated end caps) and thetubes 80 with tightly coupled end caps S1 and 82 'are strung on theconductor in the proper sequence required for appropriate finalassembly.

A bushing pair 60-61 (loosely coupled relative one another so as not toforce sealing ring 66 against the insulation covering) is strung on eachanode lead 16-18, and the stripped anode lead end 86 (FIGURE 3) ispassed into access opening 87 and is snaked out of access opening 89.With section 88 outside of the bore of tube 80 and below access opening89, end 86 is spliced to section 88 as shown, and then the splice 90 isforced back within tube 80.

The bushing pairs 60-61 are then appropriately moved on their associatedconductors and coupled to the ends 81 or 82, as the case maybe. Eachsealing ring bushing 61 is then tightly coupled to its associated endplug bushing so yto compress each sealing ring 66.

The protective cap 27 shown in FIGURE 7 is adapted to hermetically sealthe anode lead connection 91 to anode rod 13-14. This connection jointis particularly subject to corrosion-because fof the dissimilar metalsinvolved.

Cap 27 comprises a cup-shaped body 92 formed with an annular side Wall93 tocollar the connected end of the anode rod 13414. The upper end ofthe anode rod contacts the bottom wall 94 of the cup-shaped body 92.TheV annular side wall 93 is formed with a projecting lip 95 that isinternally threaded. A threaded -anode lrod bushing 96 tightly collarsthe anode nod 13-14 and is coupled to the projecting lip 95. housedwithin an annular retaining groove formed in upper lip 98 of anode rodbushing 96. Sealing ring 97 is severely compressed by tightly couplinganode rod bushing 96 relative cup-shaped body 92 by inserting spannerwrench pins in holes 75, thereby establishing a hermetic seal at itscontacting area with the anode rod. Anode lead 16-18 is sealed relativecup-shaped body 94 vby bushing pair 60-61 previously described. Allparts of protection cap 27 are preferably formed from plastics, such asKralastic and Teflon.

It should be understood that the above described arrangements are merelyillustrative of the principles of this invention, and that modificationcan be made without departing from the scope of this invention.

What is claimed is:

1. An anode assembly comprising to a rod-type anode electrode, acup-shaped body of solid insulating material formed with an annular sidewall contacting and collaring one end of the rod electrode and a bottomwall contacting and covering the collared anode end, an anode rodbushing coupled to the annular body wall and tightly collaring the anoderod, said anode rod bushing having the same internal diameter as saidside wall of said body, a rod sealing ring disposed between the body andthe inner end of said rod bushing and fitted around the electrode rod toestablish a hermetic seal in response to compression of the ring, and abushing pair of electrical insulation material hermetically fitted to anaccess opening in the bottom wall with each bushing of the pair formedwith aligned conductor feed-through holes, and a conductor sealing ringdisposed between the bushings A sealing ring 97 is of'the pair with theinner peripheral surface of the ring projecting into the passagewayformed by the conductor feed-through holes thereby to t closely aroundand to seal the conductor passing therethrough in response tocompression of the ring by the bushing pair.

2. A cathodic protection anode assembly comprising a rod-type anodeburied in an anode ground bed, a cupshaped body of insulation materialformed with an annular side wall contacting and collaring one end of theanode rod and a bottom wall contacting and covering the collared anodeend, an anode rod bushing coupled to the annular body wall and tightlycollaring the anode rod,

said anode rod bushing having the same internal diameterV as said sidewall of said body, a rod sealing ring disposed between the body and theinner end of said rod bushing and fitted around the anode rod toestablish a hermetic seal in response to compression of the ring, and abushing pair of electrical insulation material hermetically fitted to anaccess opening in the bottom wall with each bushing of the pair formedwith aligned anode lead feed- 4 through holes, and an anode lead sealingring disposed soy between the bushings `of the pair with the innerperipheral surface of the ring projecting into the passageway formed bythe anode lead feed-through holes thereby to lit closely around and toseal an anode lead passing therethrough in response to compression ofthe ring by the bushing pair.

3. A cathodic protection anode assembly comprising a rod-type anodeburied in an anode ground bed, a cupshaped body of insulation materialformed with an annular side wall contacting and collaring one end of theanode rod and a bottom Wall contacting and covering the collared anodeend, an anode rod bushing coupled to the annular body wall and tightlycollaring the anode rod, said anode rod bushing having the same internaldiameter as -said side wall of said body, a rod sealing ring disposedbetween the body and the rod bushing and fitted around.

the anode rod to establish a hermetic seal in response to compression ofthe ring, and a bushing pair of electrical insulation material includingan'end plug bushing and a sealing ring bushing seated within a.counterbore formed in the end plug bushing hermetically fitted to anaccess opening in the bottom wall with each bushing of the pair formedwith aligned anode feed-through holes, and an anode lead sealing ringdisposed between the bushings of the pair with the inner peripheralsurface of the ring projecting into the passageway formed by the anodelead feed-through holes thereby to t closely around and to seal an anodelead passing therethrough in re-` spouse to compression of the ring bythe bushing pair.

2,127,315 8/38 Thayer 204-196 2,304,210 l2/42 Scott et al 174-1022,466,997 4/49 Morris 174-93 2,616,780 11/52 Atkinson et al. 21-2.52,621,228 12/52 Tompers 174-93 2,803,602 8/57 De Cowsky et al 204-1962,926,066 2/60 Lew 21-2.5 2,926,128 '2/60 Flower 204-196 2,937,228 5/60Robinson 174-93 2,949,417 -8/60 Preiser et al 204-196 2,958,722 11/60Rubin et al. 174-93 2,972,004 2/61 Merrell et al. 174-93 3,013,101 12/61Domenach 174-19 3,020,121 2/62 Bull 21-2.5 3,022,243 2/62 Anderson204-196 3,043,765 7/62 Bryan et al. 204-196 3,058,086 10/62 Zwanzig204-196 JOHN H. MACK, Primary Examiner.

JOHN R. SPECK, JOSEPH REBOLD, MURRAY TILLMAN, Examiners.

1. AN ANODE ASSEMBLY COMPRISING TO A ROD-TYPE ANODE ELECTRODE, ACUP-SHAPED BODY OF SOLID INSULATING MATERIAL FORMED WITH AN ANNULAR SIDEWALL CONTACTING AND COLLARING ONE END OF THE ROD ELECTRODE AND A BOTTOMWALL CONTACTING AND COVERING THE COLLARED ANODE END, AN ANODE RODBUSHING COUPLED TO THE ANNULAR BODY WALL AND TIGHTLY COLLARING THE ANODEROD, SAID ANODE ROD BUSHING HAVING THE SAME INTERNAL DIAMETER AS SAIDSIDE WALL OF SAID BODY, A ROD SEALING RING DISPOSED BETWEEN THE BODY ANDTHE INNER END OF SAID ROD BUSHING AND FITTED AROUND THE ELECTRODE ROD TOESTABLISH A HERMETIC SEAL IN RESPONSE TO